1. Field of the Disclosure
The present disclosure relates to an apparatus for power line communication, and particularly, to an apparatus for power line communication, in which a communication signal is selectively output to a communication target phase among phases of a three-phase power line.
2. Description of the Background Art
Power line communication has advantages of low investment costs in view of using existing power lines without installation of another communication line, and simplified communication by connecting a plug into a socket installed on a wall. Therefore, the power line communication is considered as the most appropriate medium in various types of fields, such as home networking, home automation, remote metering, and factory automation. Particularly, remote metering using the power line communication is a technique preferred by electric power companies, in which power meter data of all consumers connected to electric wiring are metered by installing at a secondary pole transformer.
FIG. 1 is a configuration view showing remote metering using conventional power line communication.
FIG. 2 is a graph showing the amplitude of signals in the conventional power line communication.
As shown in FIG. 1, in the configuration of the remote metering using the conventional power line communication, a concentrator is installed at a secondary pole transformer and connected to a power source circuit in three phases, i.e., R, S and T phases to receive power for the purpose of the power line communication. The power of the R, S and T phases of the secondary pole transformer is applied to each consumer. An analog processor of a power line communication modem should support outputs of the three phases so that the power line communication modem applies a power line signal to each of the R, S and T phases.
Most power line communication modems are designed based on a single phase and designed to have the magnitude of power line signals, slightly lower than a reference value allowed in the law, in consideration of a variation between products, and the like. If the modem designed based on the single phase is applied to the three phases without any correction, the output driving performance of the analog processor is insufficient, and therefore, the communication performance of the modem is deteriorated. In order to prevent the deterioration of the communication performance, if the output of the analog processor is designed to be three times greater than that based on the single phase, the communication performance is improved, but the magnitude of power line communication signals exceeds the reference value allowed in the law. FIG. 2 shows a problem in that, in the case of three-phases, the magnitude of power line communication signals exceeds the reference value allowed in the law.